ePoster
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Abstracts/Presentation Description
Hamish Anderson1, Mark van Voorthuizen1, John O'Donnell1, Sarah Beck1
1Canterbury Health Laboratories, Te Whatu Ora Waitaha (Canterbury)
Introduction: Detection of myositis specific autoantibodies (MSA) is important in the diagnosis and subtyping of idiopathic inflammatory myopathies (IIM). Widespread use of the line immunoassay (LIA) for MSA detection has significant limitations due to high false positive rate. 1 Confirmatory testing is therefore vital to minimise reporting of false positive results, however anti-HMGCR antibody confirmatory assays are not widely available in Australasia.
Method: Indirect immunofluorescence (IIF) on HEp-2000® substrate was compared to immunoprecipitation (IP) in 53 samples positive for anti-HMGCR antibodies by LIA.
Results: Anti-HMGCR antibodies lead to a characteristic cell cycle dependent cytoplasmic pattern on HEp-2000® substrate. Sensitivity is 93.1% (95% CI 77.2-99.2) and specificity is 95.8% (95% CI 78.9-99.9) when compared to IP.
Conclusion: Use of IIF for confirmatory anti-HMGCR testing is an accessible and accurate option for diagnostic immunology laboratories when the gold standard IP assay is unavailable.
1. Bundell C, Rojana-Udomsart A, Mastaglia F, et al. Diagnostic performance of a commercial immunoblot assay for myositis antibody testing. Pathology. 2016; 48: 363-6
This study was my original idea (in collaboration with Mark van Voorthuizen) and I contributed significantly to all aspects of the work.
1Canterbury Health Laboratories, Te Whatu Ora Waitaha (Canterbury)
Introduction: Detection of myositis specific autoantibodies (MSA) is important in the diagnosis and subtyping of idiopathic inflammatory myopathies (IIM). Widespread use of the line immunoassay (LIA) for MSA detection has significant limitations due to high false positive rate. 1 Confirmatory testing is therefore vital to minimise reporting of false positive results, however anti-HMGCR antibody confirmatory assays are not widely available in Australasia.
Method: Indirect immunofluorescence (IIF) on HEp-2000® substrate was compared to immunoprecipitation (IP) in 53 samples positive for anti-HMGCR antibodies by LIA.
Results: Anti-HMGCR antibodies lead to a characteristic cell cycle dependent cytoplasmic pattern on HEp-2000® substrate. Sensitivity is 93.1% (95% CI 77.2-99.2) and specificity is 95.8% (95% CI 78.9-99.9) when compared to IP.
Conclusion: Use of IIF for confirmatory anti-HMGCR testing is an accessible and accurate option for diagnostic immunology laboratories when the gold standard IP assay is unavailable.
1. Bundell C, Rojana-Udomsart A, Mastaglia F, et al. Diagnostic performance of a commercial immunoblot assay for myositis antibody testing. Pathology. 2016; 48: 363-6
This study was my original idea (in collaboration with Mark van Voorthuizen) and I contributed significantly to all aspects of the work.
Speaker/Presenting Authors
Authors
Submitting/Presenting Authors
Dr Hamish Anderson - Canterbury Health Laboratories, Te Whatu Ora Waitaha (Canterbury) (Canterbury, New Zealand)